This invention relates to apparatus which can be used for general X-ray diagnostic purposes and features the capability for being quickly converted to a specialized apparatus for making arteriographic studies of the heart.
Some prior apparatus for performing these specialized cardiac procedures have an X-ray source arranged on one side of a patient supporting table and an X-ray imaging system on the other side with the source and imaging system on a mounting which enables the central X-ray beam to remain directed at the image plane for various angles at which viewing of the heart is desired. In some prior designs the patient is supported for limited lengthwise turning and longitudinal angulation relative to the X-ray beam to provide for viewing the heart at the various angles. In other designs, the X-ray source can be angulated while the patient is supported for limited lengthwise rotation or no rotation at all.
In known types of apparatus that is dedicated to making arteriographic studies the patient is supported on an X-ray transmissive tabletop which overhangs or extends in cantilever fashion from a base. The X-ray source and imaging devices are supported on the ends of the two sides of a U-shaped arm assembly to dispose them on opposite sides of the upper part of the body which rests on the cantilever tabletop. The curved base of the U-shaped arm assembly, which connects the nominally horizontal sides, is mounted for sliding in a curved path in a bearing structure or guide that is supported on a horizontal shaft. The shaft may be journalled in a floor mounted support structure. The apparatus is arranged so the normally horizontally extending sides of the U-shaped assembly project lengthwise of the patient and tabletop in the cranial to caudal direction.
In another prior art apparatus that is dedicated to making heart examinations, a C-shaped arm is carried on a floor mounted or ceiling mounted stand. The C-arm has an X-ray source mounted on one terminus and an imaging assembly mounted on the other. The arrangement is such that the arm may be passed laterally over a patient suspended in cantilever fashion on a tabletop. This arrangement permits lateral and longitudinal angulation of the source and imaging devices such that the heart may be viewed from various angles.
A significant problem with both types of apparatus discussed above is that the X-ray source and imaging device are both located in free space such that the cardioradiologist, attendants and patient are exposed to stray radiation and radiation that is scattered from the imaging device and the structural elements around it. Since the source and imaging device in conjunction with the arm must be free to move at all angles around the patient, it is not possible to totally enclose either of them to minimize stray and scattered radiation.
Another problem with mounting an X-ray source and imaging device on a U-arm or C-arm is that it is difficult to provide for angulating the X-ray source longitudinally of the patient coordinately with the imaging device. Also, since the arm approaches the patient from the head end when a U-arm is used and from the side at the head end when a C-arm is used, and there is usually a floor mounted support for the arm, the apparatus necessarily requires much space in a cardiovascular examination room. This is obviously undesirable.
Another disadvantage of some prior art heart examination systems is that when the unitarily mounted X-ray source and image device are maneuvered to the desired viewing angle there is a chance that the patient may be struck by the equipment.
Another disadvantage of the prior apparatus discussed above in that it must be made very massive to obtain the rigidity required for maintaining the X-ray beam in unswerving vibration-free alignment with the image plane. This is especially true where the X-ray source and image device are on the ends of long parallel arms. Massiveness also requires more manual or mechanical force to position the apparatus relative to a patient. The problem is aggravated by the need for the imaging system to include an image amplifier, a television camera, a spot film camera and a cine camera which have substantial total weight.
Despite the continuing redevelopment and refinement of cardiovascular and arteriographic X-ray apparatus, procedures for getting views of the entire coronary arterial system is still inconvenient and painstaking with prior apparatus.